Formation of glass-ceramic materials based on pyroxene solid solution-fluorapatite phases and their thermal expansion properties

The thermal expansion coefficients (α-values) of the glasses and glass-ceramics were determined. The α-values of the studied glasses ranged between 78 × 10−7 and 99 × 10−7 °C−1 in the (25-500 °C) temperature range and those of crystalline products ranged from 66 × 10−7 to 100 × 10−7 °C−1 in the (25-700 °C) temperature range. The data of the glasses were correlated to the internal structure of the glasses, nature and role played by glass forming cations. However, the expansivity of the crystalline glasses was mainly attributed to different factors including the crystalline phases formed and residual glassy phase.